1. Field
The present invention relates to a video conference system, a band control method, a conference control device, a video conference terminal device and a recording medium recording a program, and more particularly to a video conference system, a band control method, a conference control device, a video conference terminal device and a recording medium recording a program which can control a bandwidth.
2. Description of the Related Art
Conventionally, as a communication system which uses an IP network, there has been known a video conference system which includes a MCU (Multi point Control Unit) and video conference terminal devices. In this video conference system, conference information such as voice information and image information is transmitted or received between the MCU and the video conference terminal devices through the IP network. Here, the video conference system provides the video conference by displaying voices, images and the like corresponding to the conference information by a display part or the like which is mounted on each video conference terminal device.
However, in the network such as the Internet, a large number of people use the network for various purposes including web browsing besides users of the above-mentioned video conference. Accordingly, there may be a case where the users of the above-mentioned video conference system and the users of the network other than the users of the video conference system (hereinafter referred to as “other users”) simultaneously use the network. In such a case, according to this video conference system, depending on the use condition of the network by other users, a band which the users of the video conference system can use (hereinafter referred to as “use band”) may be changed. Accordingly, in such a video conference system, a necessary bandwidth cannot be ensured when the use band is changed thus giving rise to a possibility that the transmission/reception of voice information, image information or the like is delayed or interrupted in the course of the transmission/reception.
To overcome such a drawback, there has been proposed a conference system which performs a control of a bandwidth of a conference terminal device where, when a use band of a conference system is changed during the conference, the bandwidth of the conference terminal device is controlled corresponding to a change of the use band.
For example, there has been proposed a conference system which can, by dynamically controlling a compression rate of voice data by monitoring the congestion of the network based on a transmission/reception state of the voice data, realize the conference with voices of high quality during a usual state, and realize the conference with voices of low quality while preventing the interruption of voice or the delay of the transmission/reception of voice information during the congestion of the network.
Such a conference system controls a bandwidth in accordance with a use band for every conference terminal device.